/* Common subexpression elimination for GNU compiler.
Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998
- 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
Free Software Foundation, Inc.
This file is part of GCC.
#define REGNO_QTY_VALID_P(N) (REG_QTY (N) >= 0)
+/* Compare table_elt X and Y and return true iff X is cheaper than Y. */
+
+#define CHEAPER(X, Y) \
+ (preferable ((X)->cost, (X)->regcost, (Y)->cost, (Y)->regcost) < 0)
+
static struct table_elt *table[HASH_SIZE];
/* Chain of `struct table_elt's made so far for this function
static int constant_pool_entries_cost;
static int constant_pool_entries_regcost;
+/* Trace a patch through the CFG. */
+
+struct branch_path
+{
+ /* The basic block for this path entry. */
+ basic_block bb;
+};
+
/* This data describes a block that will be processed by
cse_extended_basic_block. */
/* Size of current branch path, if any. */
int path_size;
/* Current path, indicating which basic_blocks will be processed. */
- struct branch_path
- {
- /* The basic block for this path entry. */
- basic_block bb;
- } *path;
+ struct branch_path *path;
};
static struct table_elt *lookup (rtx, unsigned, enum machine_mode);
static struct table_elt *lookup_for_remove (rtx, unsigned, enum machine_mode);
static rtx lookup_as_function (rtx, enum rtx_code);
+static struct table_elt *insert_with_costs (rtx, struct table_elt *, unsigned,
+ enum machine_mode, int, int);
static struct table_elt *insert (rtx, struct table_elt *, unsigned,
enum machine_mode);
static void merge_equiv_classes (struct table_elt *, struct table_elt *);
return false;
case PLUS:
- if (GET_CODE (XEXP (x, 1)) != CONST_INT)
+ if (!CONST_INT_P (XEXP (x, 1)))
return false;
return fixed_base_plus_p (XEXP (x, 0));
return mention_regs (x);
}
\f
+
+/* Compute upper and lower anchors for CST. Also compute the offset of CST
+ from these anchors/bases such that *_BASE + *_OFFS = CST. Return false iff
+ CST is equal to an anchor. */
+
+static bool
+compute_const_anchors (rtx cst,
+ HOST_WIDE_INT *lower_base, HOST_WIDE_INT *lower_offs,
+ HOST_WIDE_INT *upper_base, HOST_WIDE_INT *upper_offs)
+{
+ HOST_WIDE_INT n = INTVAL (cst);
+
+ *lower_base = n & ~(targetm.const_anchor - 1);
+ if (*lower_base == n)
+ return false;
+
+ *upper_base =
+ (n + (targetm.const_anchor - 1)) & ~(targetm.const_anchor - 1);
+ *upper_offs = n - *upper_base;
+ *lower_offs = n - *lower_base;
+ return true;
+}
+
+/* Insert the equivalence between ANCHOR and (REG + OFF) in mode MODE. */
+
+static void
+insert_const_anchor (HOST_WIDE_INT anchor, rtx reg, HOST_WIDE_INT offs,
+ enum machine_mode mode)
+{
+ struct table_elt *elt;
+ unsigned hash;
+ rtx anchor_exp;
+ rtx exp;
+
+ anchor_exp = GEN_INT (anchor);
+ hash = HASH (anchor_exp, mode);
+ elt = lookup (anchor_exp, hash, mode);
+ if (!elt)
+ elt = insert (anchor_exp, NULL, hash, mode);
+
+ exp = plus_constant (reg, offs);
+ /* REG has just been inserted and the hash codes recomputed. */
+ mention_regs (exp);
+ hash = HASH (exp, mode);
+
+ /* Use the cost of the register rather than the whole expression. When
+ looking up constant anchors we will further offset the corresponding
+ expression therefore it does not make sense to prefer REGs over
+ reg-immediate additions. Prefer instead the oldest expression. Also
+ don't prefer pseudos over hard regs so that we derive constants in
+ argument registers from other argument registers rather than from the
+ original pseudo that was used to synthesize the constant. */
+ insert_with_costs (exp, elt, hash, mode, COST (reg), 1);
+}
+
+/* The constant CST is equivalent to the register REG. Create
+ equivalences between the two anchors of CST and the corresponding
+ register-offset expressions using REG. */
+
+static void
+insert_const_anchors (rtx reg, rtx cst, enum machine_mode mode)
+{
+ HOST_WIDE_INT lower_base, lower_offs, upper_base, upper_offs;
+
+ if (!compute_const_anchors (cst, &lower_base, &lower_offs,
+ &upper_base, &upper_offs))
+ return;
+
+ /* Ignore anchors of value 0. Constants accessible from zero are
+ simple. */
+ if (lower_base != 0)
+ insert_const_anchor (lower_base, reg, -lower_offs, mode);
+
+ if (upper_base != 0)
+ insert_const_anchor (upper_base, reg, -upper_offs, mode);
+}
+
+/* We need to express ANCHOR_ELT->exp + OFFS. Walk the equivalence list of
+ ANCHOR_ELT and see if offsetting any of the entries by OFFS would create a
+ valid expression. Return the cheapest and oldest of such expressions. In
+ *OLD, return how old the resulting expression is compared to the other
+ equivalent expressions. */
+
+static rtx
+find_reg_offset_for_const (struct table_elt *anchor_elt, HOST_WIDE_INT offs,
+ unsigned *old)
+{
+ struct table_elt *elt;
+ unsigned idx;
+ struct table_elt *match_elt;
+ rtx match;
+
+ /* Find the cheapest and *oldest* expression to maximize the chance of
+ reusing the same pseudo. */
+
+ match_elt = NULL;
+ match = NULL_RTX;
+ for (elt = anchor_elt->first_same_value, idx = 0;
+ elt;
+ elt = elt->next_same_value, idx++)
+ {
+ if (match_elt && CHEAPER (match_elt, elt))
+ return match;
+
+ if (REG_P (elt->exp)
+ || (GET_CODE (elt->exp) == PLUS
+ && REG_P (XEXP (elt->exp, 0))
+ && GET_CODE (XEXP (elt->exp, 1)) == CONST_INT))
+ {
+ rtx x;
+
+ /* Ignore expressions that are no longer valid. */
+ if (!REG_P (elt->exp) && !exp_equiv_p (elt->exp, elt->exp, 1, false))
+ continue;
+
+ x = plus_constant (elt->exp, offs);
+ if (REG_P (x)
+ || (GET_CODE (x) == PLUS
+ && IN_RANGE (INTVAL (XEXP (x, 1)),
+ -targetm.const_anchor,
+ targetm.const_anchor - 1)))
+ {
+ match = x;
+ match_elt = elt;
+ *old = idx;
+ }
+ }
+ }
+
+ return match;
+}
+
+/* Try to express the constant SRC_CONST using a register+offset expression
+ derived from a constant anchor. Return it if successful or NULL_RTX,
+ otherwise. */
+
+static rtx
+try_const_anchors (rtx src_const, enum machine_mode mode)
+{
+ struct table_elt *lower_elt, *upper_elt;
+ HOST_WIDE_INT lower_base, lower_offs, upper_base, upper_offs;
+ rtx lower_anchor_rtx, upper_anchor_rtx;
+ rtx lower_exp = NULL_RTX, upper_exp = NULL_RTX;
+ unsigned lower_old, upper_old;
+
+ if (!compute_const_anchors (src_const, &lower_base, &lower_offs,
+ &upper_base, &upper_offs))
+ return NULL_RTX;
+
+ lower_anchor_rtx = GEN_INT (lower_base);
+ upper_anchor_rtx = GEN_INT (upper_base);
+ lower_elt = lookup (lower_anchor_rtx, HASH (lower_anchor_rtx, mode), mode);
+ upper_elt = lookup (upper_anchor_rtx, HASH (upper_anchor_rtx, mode), mode);
+
+ if (lower_elt)
+ lower_exp = find_reg_offset_for_const (lower_elt, lower_offs, &lower_old);
+ if (upper_elt)
+ upper_exp = find_reg_offset_for_const (upper_elt, upper_offs, &upper_old);
+
+ if (!lower_exp)
+ return upper_exp;
+ if (!upper_exp)
+ return lower_exp;
+
+ /* Return the older expression. */
+ return (upper_old > lower_old ? upper_exp : lower_exp);
+}
+\f
/* Look in or update the hash table. */
/* Remove table element ELT from use in the table.
struct table_elt *p
= lookup (x, SAFE_HASH (x, VOIDmode), GET_MODE (x));
- /* If we are looking for a CONST_INT, the mode doesn't really matter, as
- long as we are narrowing. So if we looked in vain for a mode narrower
- than word_mode before, look for word_mode now. */
- if (p == 0 && code == CONST_INT
- && GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (word_mode))
- {
- x = copy_rtx (x);
- PUT_MODE (x, word_mode);
- p = lookup (x, SAFE_HASH (x, VOIDmode), word_mode);
- }
-
if (p == 0)
return 0;
return 0;
}
-/* Insert X in the hash table, assuming HASH is its hash code
- and CLASSP is an element of the class it should go in
- (or 0 if a new class should be made).
- It is inserted at the proper position to keep the class in
- the order cheapest first.
+/* Insert X in the hash table, assuming HASH is its hash code and
+ CLASSP is an element of the class it should go in (or 0 if a new
+ class should be made). COST is the code of X and reg_cost is the
+ cost of registers in X. It is inserted at the proper position to
+ keep the class in the order cheapest first.
MODE is the machine-mode of X, or if X is an integer constant
with VOIDmode then MODE is the mode with which X will be used.
If necessary, update table showing constant values of quantities. */
-#define CHEAPER(X, Y) \
- (preferable ((X)->cost, (X)->regcost, (Y)->cost, (Y)->regcost) < 0)
-
static struct table_elt *
-insert (rtx x, struct table_elt *classp, unsigned int hash, enum machine_mode mode)
+insert_with_costs (rtx x, struct table_elt *classp, unsigned int hash,
+ enum machine_mode mode, int cost, int reg_cost)
{
struct table_elt *elt;
elt->exp = x;
elt->canon_exp = NULL_RTX;
- elt->cost = COST (x);
- elt->regcost = approx_reg_cost (x);
+ elt->cost = cost;
+ elt->regcost = reg_cost;
elt->next_same_value = 0;
elt->prev_same_value = 0;
elt->next_same_hash = table[hash];
return elt;
}
+
+/* Wrap insert_with_costs by passing the default costs. */
+
+static struct table_elt *
+insert (rtx x, struct table_elt *classp, unsigned int hash,
+ enum machine_mode mode)
+{
+ return
+ insert_with_costs (x, classp, hash, mode, COST (x), approx_reg_cost (x));
+}
+
\f
/* Given two equivalence classes, CLASS1 and CLASS2, put all the entries from
CLASS2 into CLASS1. This is done when we have reached an insn which makes
{
struct check_dependence_data *d = (struct check_dependence_data *) data;
if (*x && MEM_P (*x))
- return canon_true_dependence (d->exp, d->mode, d->addr, *x,
+ return canon_true_dependence (d->exp, d->mode, d->addr, *x, NULL_RTX,
cse_rtx_varies_p);
else
return 0;
goto repeat;
}
- hash += hash_rtx_cb (XEXP (x, i), 0, do_not_record_p,
+ hash += hash_rtx_cb (XEXP (x, i), VOIDmode, do_not_record_p,
hash_arg_in_memory_p,
have_reg_qty, cb);
break;
case 'E':
for (j = 0; j < XVECLEN (x, i); j++)
- hash += hash_rtx_cb (XVECEXP (x, i, j), 0, do_not_record_p,
+ hash += hash_rtx_cb (XVECEXP (x, i, j), VOIDmode, do_not_record_p,
hash_arg_in_memory_p,
have_reg_qty, cb);
break;
}
if (GET_CODE (x) == PLUS
- && GET_CODE (XEXP (x, 1)) == CONST_INT
+ && CONST_INT_P (XEXP (x, 1))
&& REG_P (XEXP (x, 0))
&& REGNO_QTY_VALID_P (REGNO (XEXP (x, 0))))
{
if (y != 0
&& (inner_const = equiv_constant (XEXP (y, 1))) != 0
- && GET_CODE (inner_const) == CONST_INT
+ && CONST_INT_P (inner_const)
&& INTVAL (inner_const) != 0)
folded_arg0 = gen_rtx_IOR (mode_arg0, XEXP (y, 0), inner_const);
}
the smallest negative number this would overflow: depending
on the mode, this would either just be the same value (and
hence not save anything) or be incorrect. */
- if (const_arg1 != 0 && GET_CODE (const_arg1) == CONST_INT
+ if (const_arg1 != 0 && CONST_INT_P (const_arg1)
&& INTVAL (const_arg1) < 0
/* This used to test
case MINUS:
/* If we have (MINUS Y C), see if Y is known to be (PLUS Z C2).
If so, produce (PLUS Z C2-C). */
- if (const_arg1 != 0 && GET_CODE (const_arg1) == CONST_INT)
+ if (const_arg1 != 0 && CONST_INT_P (const_arg1))
{
rtx y = lookup_as_function (XEXP (x, 0), PLUS);
- if (y && GET_CODE (XEXP (y, 1)) == CONST_INT)
+ if (y && CONST_INT_P (XEXP (y, 1)))
return fold_rtx (plus_constant (copy_rtx (y),
-INTVAL (const_arg1)),
NULL_RTX);
if the intermediate operation's result has only one reference. */
if (REG_P (folded_arg0)
- && const_arg1 && GET_CODE (const_arg1) == CONST_INT)
+ && const_arg1 && CONST_INT_P (const_arg1))
{
int is_shift
= (code == ASHIFT || code == ASHIFTRT || code == LSHIFTRT);
rtx y, inner_const, new_const;
+ rtx canon_const_arg1 = const_arg1;
enum rtx_code associate_code;
if (is_shift
|| INTVAL (const_arg1) < 0))
{
if (SHIFT_COUNT_TRUNCATED)
- const_arg1 = GEN_INT (INTVAL (const_arg1)
- & (GET_MODE_BITSIZE (mode) - 1));
+ canon_const_arg1 = GEN_INT (INTVAL (const_arg1)
+ & (GET_MODE_BITSIZE (mode)
+ - 1));
else
break;
}
break;
inner_const = equiv_constant (fold_rtx (XEXP (y, 1), 0));
- if (!inner_const || GET_CODE (inner_const) != CONST_INT)
+ if (!inner_const || !CONST_INT_P (inner_const))
break;
/* Don't associate these operations if they are a PLUS with the
associate_code = (is_shift || code == MINUS ? PLUS : code);
new_const = simplify_binary_operation (associate_code, mode,
- const_arg1, inner_const);
+ canon_const_arg1,
+ inner_const);
if (new_const == 0)
break;
of shifts. */
if (is_shift
- && GET_CODE (new_const) == CONST_INT
+ && CONST_INT_P (new_const)
&& INTVAL (new_const) >= GET_MODE_BITSIZE (mode))
{
/* As an exception, we can turn an ASHIFTRT of this
if (GET_CODE (x) == SUBREG)
{
+ enum machine_mode mode = GET_MODE (x);
+ enum machine_mode imode = GET_MODE (SUBREG_REG (x));
rtx new_rtx;
/* See if we previously assigned a constant value to this SUBREG. */
|| (new_rtx = lookup_as_function (x, CONST_FIXED)) != 0)
return new_rtx;
+ /* If we didn't and if doing so makes sense, see if we previously
+ assigned a constant value to the enclosing word mode SUBREG. */
+ if (GET_MODE_SIZE (mode) < GET_MODE_SIZE (word_mode)
+ && GET_MODE_SIZE (word_mode) < GET_MODE_SIZE (imode))
+ {
+ int byte = SUBREG_BYTE (x) - subreg_lowpart_offset (mode, word_mode);
+ if (byte >= 0 && (byte % UNITS_PER_WORD) == 0)
+ {
+ rtx y = gen_rtx_SUBREG (word_mode, SUBREG_REG (x), byte);
+ new_rtx = lookup_as_function (y, CONST_INT);
+ if (new_rtx)
+ return gen_lowpart (mode, new_rtx);
+ }
+ }
+
+ /* Otherwise see if we already have a constant for the inner REG. */
if (REG_P (SUBREG_REG (x))
&& (new_rtx = equiv_constant (SUBREG_REG (x))) != 0)
- return simplify_subreg (GET_MODE (x), SUBREG_REG (x),
- GET_MODE (SUBREG_REG (x)), SUBREG_BYTE (x));
+ return simplify_subreg (mode, new_rtx, imode, SUBREG_BYTE (x));
return 0;
}
rtx src_eqv_here;
rtx src_const = 0;
rtx src_related = 0;
+ bool src_related_is_const_anchor = false;
struct table_elt *src_const_elt = 0;
int src_cost = MAX_COST;
int src_eqv_cost = MAX_COST;
{
rtx width = XEXP (SET_DEST (sets[i].rtl), 1);
- if (GET_CODE (src) == CONST_INT
- && GET_CODE (width) == CONST_INT
+ if (CONST_INT_P (src)
+ && CONST_INT_P (width)
&& INTVAL (width) < HOST_BITS_PER_WIDE_INT
&& (INTVAL (src) & ((HOST_WIDE_INT) (-1) << INTVAL (width))))
src_folded
/* See if we have a CONST_INT that is already in a register in a
wider mode. */
- if (src_const && src_related == 0 && GET_CODE (src_const) == CONST_INT
+ if (src_const && src_related == 0 && CONST_INT_P (src_const)
&& GET_MODE_CLASS (mode) == MODE_INT
&& GET_MODE_BITSIZE (mode) < BITS_PER_WORD)
{
enum machine_mode wider_mode;
for (wider_mode = GET_MODE_WIDER_MODE (mode);
- GET_MODE_BITSIZE (wider_mode) <= BITS_PER_WORD
+ wider_mode != VOIDmode
+ && GET_MODE_BITSIZE (wider_mode) <= BITS_PER_WORD
&& src_related == 0;
wider_mode = GET_MODE_WIDER_MODE (wider_mode))
{
value. */
if (flag_expensive_optimizations && ! src_related
- && GET_CODE (src) == AND && GET_CODE (XEXP (src, 1)) == CONST_INT
+ && GET_CODE (src) == AND && CONST_INT_P (XEXP (src, 1))
&& GET_MODE_SIZE (mode) < UNITS_PER_WORD)
{
enum machine_mode tmode;
}
#endif /* LOAD_EXTEND_OP */
+ /* Try to express the constant using a register+offset expression
+ derived from a constant anchor. */
+
+ if (targetm.const_anchor
+ && !src_related
+ && src_const
+ && GET_CODE (src_const) == CONST_INT)
+ {
+ src_related = try_const_anchors (src_const, mode);
+ src_related_is_const_anchor = src_related != NULL_RTX;
+ }
+
+
if (src == src_folded)
src_folded = 0;
{
src_related_cost = COST (src_related);
src_related_regcost = approx_reg_cost (src_related);
+
+ /* If a const-anchor is used to synthesize a constant that
+ normally requires multiple instructions then slightly prefer
+ it over the original sequence. These instructions are likely
+ to become redundant now. We can't compare against the cost
+ of src_eqv_here because, on MIPS for example, multi-insn
+ constants have zero cost; they are assumed to be hoisted from
+ loops. */
+ if (src_related_is_const_anchor
+ && src_related_cost == src_cost
+ && src_eqv_here)
+ src_related_cost--;
}
}
{
rtx width = XEXP (SET_DEST (sets[i].rtl), 1);
- if (src_const != 0 && GET_CODE (src_const) == CONST_INT
- && GET_CODE (width) == CONST_INT
+ if (src_const != 0 && CONST_INT_P (src_const)
+ && CONST_INT_P (width)
&& INTVAL (width) < HOST_BITS_PER_WIDE_INT
&& ! (INTVAL (src_const)
& ((HOST_WIDE_INT) (-1) << INTVAL (width))))
elt = insert (dest, sets[i].src_elt,
sets[i].dest_hash, GET_MODE (dest));
+ /* If this is a constant, insert the constant anchors with the
+ equivalent register-offset expressions using register DEST. */
+ if (targetm.const_anchor
+ && REG_P (dest)
+ && SCALAR_INT_MODE_P (GET_MODE (dest))
+ && GET_CODE (sets[i].src_elt->exp) == CONST_INT)
+ insert_const_anchors (dest, sets[i].src_elt->exp, GET_MODE (dest));
+
elt->in_memory = (MEM_P (sets[i].inner_dest)
&& !MEM_READONLY_P (sets[i].inner_dest));
}
};
+static bool
+gate_handle_cse_after_global_opts (void)
+{
+ return optimize > 0 && flag_rerun_cse_after_global_opts;
+}
+
+/* Run second CSE pass after loop optimizations. */
+static unsigned int
+rest_of_handle_cse_after_global_opts (void)
+{
+ int save_cfj;
+ int tem;
+
+ /* We only want to do local CSE, so don't follow jumps. */
+ save_cfj = flag_cse_follow_jumps;
+ flag_cse_follow_jumps = 0;
+
+ rebuild_jump_labels (get_insns ());
+ tem = cse_main (get_insns (), max_reg_num ());
+ purge_all_dead_edges ();
+ delete_trivially_dead_insns (get_insns (), max_reg_num ());
+
+ cse_not_expected = !flag_rerun_cse_after_loop;
+
+ /* If cse altered any jumps, rerun jump opts to clean things up. */
+ if (tem == 2)
+ {
+ timevar_push (TV_JUMP);
+ rebuild_jump_labels (get_insns ());
+ cleanup_cfg (0);
+ timevar_pop (TV_JUMP);
+ }
+ else if (tem == 1)
+ cleanup_cfg (0);
+
+ flag_cse_follow_jumps = save_cfj;
+ return 0;
+}
+
+struct rtl_opt_pass pass_cse_after_global_opts =
+{
+ {
+ RTL_PASS,
+ "cse_local", /* name */
+ gate_handle_cse_after_global_opts, /* gate */
+ rest_of_handle_cse_after_global_opts, /* execute */
+ NULL, /* sub */
+ NULL, /* next */
+ 0, /* static_pass_number */
+ TV_CSE, /* tv_id */
+ 0, /* properties_required */
+ 0, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ TODO_df_finish | TODO_verify_rtl_sharing |
+ TODO_dump_func |
+ TODO_ggc_collect |
+ TODO_verify_flow /* todo_flags_finish */
+ }
+};